"The only one responsible for Sinai is Egypt, and Egypt will do everything in its power to deal with terror. Its success will prevent a bigger attack," Amos Gilad, a top official in Israel`s defence ministry, told public radio.

Speaking just hours after Egypt`s military said it launched air strikes in northern Sinai, killing 20 militants, Gilad said Cairo had grasped the nettle and begun to take action.

"These extremist organisations can harm the entire Middle East, it is not just against Egypt," he said. "The penny has dropped in Egypt, their level of awareness has been heightened. They are moving to action," he said.

"We must to keep an eye on the future and see if there is real root surgery against terror."

Wednesday`s operation launched by the Egyptian military on villages near Gaza comes three days after a deadly attack on a border post which was blamed on Islamic extremists.

In Sunday`s attack, the gunmen commandeered two armoured vehicles which they crashed over the frontier into Israel. One explosives-laden truck blew up of its own accord, while the second was stopped by an Israeli air strike. (M014)